Malawi authorities on Monday said they had arrested former army chief Henry Odillo and another senior officer over corruption charges, after they allegedly authorised payments to a firm that did not supply services to the military.

The southern African country's Anti-Corruption Bureau (ACB) said it had found that army Commander General Odillo and Lieutenant-Colonel Clement Kafuwa authorised payments of $4.4 million to Thuso Investments "for the supply of blank ammunition which was never delivered".

The ACB, which is prosecuting scores of civil servants involved in a corruption scandal dubbed Cashgate in Malawi, said the pair would be charged with a raft of offences including abuse of public office and money laundering, and that they would soon face court.

Odillo was Malawi's army commander under president Bingu wa Mutharika, who died in office in 2012, and his successor Joyce Banda.

Peter Mutharika, who has been president since 2014, fired Odillo after defeating Banda in last year's presidential race.

The Cashgate scandal, in which over $30 million was stolen from state coffers, prompted foreign donors, who provide around 40 percent of Malawi's budget, to pull the plug on aid worth around $150 million (135 million euros).

A number of government officials implicated in the fraud are facing criminal charges, and at least two officials have been convicted.